Widespread lockdowns during the coronavirus disease 2019 (COVID-19) pandemic largely limited children’s exposure to respiratory syncytial virus (RSV). This gap in immunity, combined with the reopening of childcare centers and schools, has caused RSV cases to increase worldwide.
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What is RSV?
RSV is a common respiratory virus that usually causes cold-like symptoms such as a runny nose, cough, sneezing, loss of appetite, fever and, in some cases, wheezing. Symptoms of RSV usually appear four to six days after the initial infection.
RSV can also cause severe symptoms that will require hospitalization. A child who has trouble eating, breathing rapidly, and/or has contractions in the muscles between the ribs and/or neck muscles while breathing should be taken to the emergency department immediately.
In addition to the acute effects of this infection in children, a history of severe RSV disease also increases the risk of recurrent wheezing, asthma, reduced respiratory function, and allergic sensitization later in life. These long-term respiratory effects can have a significant impact on the child’s overall quality of life, as well as increase their use of healthcare resources throughout life.
Prevalence of RSV
By the time a child reaches two years of age, it is very likely that they have been infected with RSV at some point. In fact, more than 50% of children will be infected with RSV by the time they reach one year of age.
Despite the prevalence of this virus, especially among young children, one to two out of every 100 RSV-infected children younger than six months will require hospitalization. Some of the different factors that increase the risk of severe RSV infection include prematurity, low birth weight, exposure to cigarette smoke, as well as the presence of certain comorbidities such as chronic respiratory, cardiovascular or immune diseases.
In the United States, RSV infections are responsible for 100-300 deaths in children under five each year and more than 58,000 hospitalizations. Worldwide, RSV is the most common cause of respiratory-related death in infants.
Treatments and vaccines
To date, there is still no specific treatment available for RSV other than symptomatic care. In addition to making sure infected children stay hydrated, parents and health care professionals can also administer over-the-counter medications such as ibuprofen and acetaminophen to reduce fever and pain. Children who are severely ill with RSV may be admitted to the hospital for supplemental oxygen or mechanical ventilation.
Currently, there is no vaccine available to prevent RSV infection. However, recent advances in the development of vaccines against RSV may allow their approval in the near future.
On November 1, 2022, Pfizer announced the effectiveness of its bivalent RSV vaccine when administered to pregnant women during the late second or third trimester. More specifically, these clinical trials reported that more than 82% of children were protected from severe RSV disease during the first four to six weeks of life, and more than 69% retained this protection at six months of age.
The threat of a “tripledemia”
RSV spikes in children usually occur during the winter; however, the current epidemic has appeared much earlier than usual, with a high rate of RSV cases reported in September and October this year. In addition to the strain of unusually severe RSV cases on healthcare systems, the simultaneous circulation of both influenza and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19, has the potential to create a ‘tripledemia’ this winter.
Like RSV, an increasing number of flu cases have also been reported in an untimely fashion earlier this year. In addition, the continued emergence of new immune-evasive variants of SARS-CoV-2, with the Omicron BA.5 subvariant currently the dominant circulating strain, will likely increase the rate of COVID-19 cases as we approach the winter
How to prevent RSV
Like other respiratory viruses, RSV is primarily transmitted through aerosol droplets or direct contact with contaminated objects. Thus, strict hygiene rules including careful and frequent hand washing, wearing masks, and social distancing in crowds can help prevent the spread of RSV and other circulating viruses this winter. The US Centers for Disease Control and Prevention (CDC) also advises parents to limit close contact with people suffering from cold-like symptoms.
In young children, breastfeeding has also been shown to significantly mitigate the severe effects of RSV infection. Because almost all mothers have been exposed to RSV in their lifetime, breastfeeding allows the passage of anti-RSV antibodies that protect infants from the severe effects of this disease.
A recent Italian national prospective cohort study found that non-breastfed infants had a twofold greater risk of being hospitalized with RSV bronchiolitis during the first year of life compared with breastfed infants.